GReddy's Type R Blow Off Valve (BOV) is a simple, yet powerful design. The GReddy Type R Blow Off Valve is made from Billet and Cast Aluminum. The GReddy Type R Blow Off Valve uses an oversized 47mm Housing that is Intended for Engines that produce more than 400 horsepower and over 12lbs of Boost. You can adjust the Pressure Relief by simply turning the knob on the Top. The Stock Spring Type R Blow Off Valve (BOV) Holds up to 18lbs of Boost. If your Turbo Runs Boost levels from 16lbs up, you can purchase the GReddy Stiff Spring Type R Blow Off Valve. You will need to purchase a Steel or Aluminum BOV Mounting Flange to Properly Install The GReddy Type R Universal Kit.